Hand-held ophthalmoscope

US4220401A · kind A · utility

Assignee

• Carl Zeiss Stiftung · DE

Inventor

• Franz Muchel · Oberkochen, DE

Key dates

• Filing date: Apr 12, 1978
• Grant date: Sep 2, 1980
• Expiry date: Apr 12, 1998

Classification

• Technology area (CPC A): Human Necessities
• CPC primary: A61B3/1208
• WIPO field: Medical technology
• WIPO sector: Instruments

Abstract

A hand-held ophthalmoscope having a handle part and a head part, with an illuminating device in the handle part. In the head part is an imaging lens system for producing an image of the fundus of the eye being examined, and an axially displaceable optical system for focussing the image of the fundus at infinity. The illuminating device in the handle has a source of light and a condenser and a field diaphragm. There is an optical system for imaging the field diaphragm in the key of the patient. A test mark is pivotally mounted on the mount of the axially displaceable optical system in the head portion of the device, and may be moved into cooperative relation to a scale. Preferably the optical system for producing the image of the fundus, and the partial optical system for imaging the field diaphragm or the test mark, have the same focal length. Preferably also there is an image erecting prism between the optical system which serves to produce the image of the fundus and the optical system which serves to focus the image of the fundus at infinity.